1. Field of the Invention
The present invention relates to a lubricating structure of a planetary gear mechanism which introduces lubricating oil into a double pinion type planetary gear mechanism for an automatic transmission of a vehicle.
2. Description of the Prior Art
Conventionally, many of planetary gear mechanisms provided in automatic transmissions have been used more frequently and rotated at higher speeds as compared with other rotary members in the automatic transmissions. For this reason, an oil catch plate has been generally provided on a side face of a carrier in the planetary gear mechanism so as to lead lubricating oil to bearing members that support pinion shafts in the planetary gear mechanism and the surfaces of teeth to lubricate them.
By equipping the planetary gear mechanism with the oil catch plate as mentioned above, it is possible to catch a large amount of oil splashing from the center of a shaft and to store the caught oil at a position away from the center of the shaft, and hence a large amount of oil has been introduced as lubricating oil through openings of a lubricating oil introducing holes formed in a side face of a carrier plate through action of relatively high centrifugal oil pressure.
In the case of a planetary gear mechanism in which a single pinion is engaged with a sun gear and a ring gear, i.e. a single pinion type planetary gear mechanism among the above-mentioned planetary gear mechanisms equipped with the oil catch plate, the distances from a plurality of pinion shafts arranged in the circumferential direction to the axis of the carrier are equal, and hence lubricating oil caught by the oil catch plate is uniformly supplied to the pinion shafts.
However, in the case of a double pinion type planetary gear mechanism or Ravigneaus type planetary gear mechanism, the distance from the shaft of a pinion engaged with the ring gear to the axis of the carrier of the planetary gear mechanism and the distance from the shaft of a pinion engaged with the sun gear to the axis of the carrier of the planetary gear mechanism are different from each other. Thus, lubricating oil caught by the oil catch plate is supplied first to a lubricating oil introducing hole of the pinion shaft located on the outer diameter side of the shaft of the planetary gear mechanism, and then lubricating oil that remains above the amount of lubricating oil that can be supplied to the pinion shaft on the outer diameter side is introduced to a lubricating oil introducing hole of the pinion shaft on the inner diameter side.
As a result, in the case where the amount of lubricating oil caught by the oil catch plate is less than the amount of lubricating oil that can be supplied to the outer diameter side pinion shaft, lubricating oil is not supplied to the inner diameter side pinion shaft, which may decrease the durability of the bearing section of the pinion shaft on the inner diameter side.
To solve this problem, there has been proposed a planetary gear mechanism in Japanese Laid-Open Patent Publication (Kokai) No. 2002-286119. In this planetary gear mechanism, the oil catch plate is formed with an introducing section for introducing lubricating oil to the outer diameter side pinion shaft and an introducing section for lubricating oil to the inner diameter side pinion shaft are configured as chambers independent of each other so that lubricating oil can be supplied to the inner diameter side pinion shaft irrespective of the amount of lubricating oil that can be supplied to the outer diameter side pinion shaft.
However, in the double pinion type planetary gear mechanism or Ravigneaus type planetary gear mechanism, if the oil catch plate is formed with the respective introducing sections for supplying lubricating oil to the pinion shaft on the outer diameter side and the pinion shaft on the inner diameter side, the outer periphery of the oil catch plate is complicated in shape, resulting in a low degree of design freedom. For example, it is difficult to dispose sealing members for improving the sealing capability of the lubricating oil introducing sections on the outer peripheries of the introducing sections of the oil catch plate.